1. Field of the Invention
The present invention relates to an electric brake device of a type equipped with a parking lock mechanism and, more particularly, to the technology of preventing the electric brake device from being frozen with no need of releasing a braking force.
2. Description of Related Art
In general, a vehicle is inhibited from moving with the utilization of a parking brake that is mechanically independent from a so-called foot operated brake (also called “service brake”). However, particularly during the winter season and at cold districts, it often occurs that the parking brake may be frozen enough to make it difficult to release. Accordingly, a suggestion has been made that at some cold district, if without the parking brake being used at the time of parking of a vehicle, an engagement member in an automatic transmission is engaged with a to-be-engaged member with, for example, the automatic transmission set to a parking range, the movement of the vehicle is simply prevented.
Also, another suggestion has been made that if at some cold district, in order to avoid a freezing of an electric parking brake while the vehicle is parked, a sensor for detecting the ambient temperature of the vehicle detects a temperature at which the freezing takes place, the electric parking brake can be released. In this connection, see, for example, the patent document 1 listed below.
[Patent Document 1] JP Laid-open Patent Publication No. 2005-082035